ARAN El D^. 
By H. R. HOGG, M.A. 
(Plate 2i). 
Up to the present time very few specimens of this group from the desert and 
sandy country of Central Australia have been seen by zoologists, and its character¬ 
istics are almost entirely unknown. 
The Horn Expedition has now brought down some 150 specimens collected 
througliout the whole route traversed north of the railway terminus at Oodnadatta. 
These it will be seen are well distributed over the various tribes of the order, 
and comprise 57 species, representative of 36 genera. 
While nearly one-third of the species are hitherto undescribed, they present 
a general analogy to those from the coastal districts of New South Wales and 
Queensland, exhibiting here and there interesting variations in what are clearly 
co-ordinate types. 
The differences in shape and measurement are such as might be expected to 
be developed during an isolation extending over a comparatively long period, 
isolation no doubt caused by intervening tracts of country, which even if no less 
barren than their present habitat, by change of vegetation and consequent insect 
life and food have proved an efficient barrier to migration. They consist chiefly of 
such points as longer or shorter legs, relative distances and sizes of eyes, bespining, 
absence of pattern, and shapes of genital organs, rather than differences in 
colouring which might naturally be looked for among diflerently coloured soils. 
The preponderance in number, judged by the specimens brought down, would 
appear to lie with a small ring-legged Lycosa (Z. pulveresparsa, L. Koch) and the 
large orb-weaving Nephilie, while Phrictus crassipes^ L. Koch, the giant of the 
Territelarise or hole dwellers, seems to have been fi’equently secured at Alice 
Springs; the last-named spider being notable as found by Professor Spencer to be 
provided with stridulating organs similar to those discovered by Professor James 
Wood Mason* in his Mygale stridulans from Assam. 
* Proc. Ab. Soc. Bengal, 1876, and Trans. Ent. Soc. of London, 1877, p. 281. 
